Depth indicating means for a tractor supported tool

ABSTRACT

A depth indicator is associated with a tractor. The depth indicator includes an above depth indicating circuit, an at depth indicating circuit and a below depth indicating circuit, with each circuit including visual indicators which are associated with each other so that once energized, a visual indicator will remain energized until another visual indicator is energized. 
     A tractor mounted ripper tool employs a programmable control device to change the angular attitude of the ripper blade at a preselected depth. 
     The control device positions a diverter valve to alternately apply fluid power between a depth positioning power cylinder and a pitch positioning power cylinder such that the attitude of the ripper blade will automatically be changed between a penetrating mode and a ripping mode at a preselected depth. A depth control circuit having a depth sensor switch and a depth selector switch detects the vertical displacement of the ripper tool and provides a command at a preselected depth. A pitch control circuit having a pitch sensor switch and a pitch selector switch detects the angular displacement of the ripper tool and provides a command at a preselected pitch. A control relay is connected to the depth and pitch control circuits and is responsive to the commands thereof to shift the position of the diverter valve and direct fluid power from the depth positioning cylinder to the pitch positioning cylinder when the ripper tool is detected at a preselected depth and alternately shifts the diverter valve to direct fluid power to the depth positioning cylinder when the ripper tool is detected to a preselected pitch. A complementary pair of control circuits repositions the ripper tool when moving in the opposite direction.

BACKGROUND OF THE INVENTION

This is a division of application Ser. No. 570,034, filed Apr. 21, 1975,now U.S. Pat. No. 4,044,838.

Ripper devices are mounted on tractors and are pulled thereby to break apath through the ground and fracture the ground to a certain depth. Suchdevices are generally in the form of an upstanding shank having a chiselshaped blade at its lower end and attached at its upper end to thetractor through a series of links forming an articulated tool mount.Power cylinders are operatively connected to the tool mount to changethe attitude and depth of penetration of the ripper blade. In operation,the ripper blade is elevated to a position out of the ground until thesubject ground site is arrived at. At the proper site, the tractor movesforward while the ripper tool is depressed into the ground in apenetrating mode until it reaches the working or ripping depth.Experience has shown that the angle at which the ripper blade ispositioned with respect to the path of the tractor affects theefficiency and life of the ripper blade. It has been determined that theripper blade performs best if it is at a steep angle of attack whenmoving downward to the ripping depth in the penetrating mode. It hasalso been determined that the life of the blade is increased if theblade is at a shallow angle of attack when in the ripping or workingmode of operation. Thus, it is desirable to change the angle of attackof the ripper blade between the penetrating mode and the ripping mode.

Generally, the depth at which this change is made is derived empiricallyfor a given ground structure. Similarly, the most desirable attitudeangles of the ripper blade in the penetrating and ripping modes maychange, depending on the particular ground structure.

When a number of tractor operators are engaged in working the sameground plot, it is desirable that they all be working under the sameattitude and depth parameters. These parameters are chosen by asupervising operator or "dirt boss". Heretofore, the various operatorshad to visually rely on the relative position of the ripper shank, toolmount and tractor to determine the depth and attitude of the ripperblade. Obviously, this provided varying degrees of accuracy in reachingand maintaining the prescribed depth and pitch for the ripper blade.

It is in the course of the above that this invention is concerned,wherein the expertise of an experienced supervisor may be used to bestposition the ripper blade for individual tractors by preselectingsettings on an automatic control device and where the preselectedconditions will be carried out without the conscious effort of thetractor operator.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to provide anautomatic control device which may be programmed to change the angularattitude of a ripper tool at a preselected depth.

Another object is to provide such a control device to change the angularattitude of a ripper tool from one preselected angle to anotherpreselected angle at a preselected depth.

Yet another object is to provide an automatic control device forchanging the angular attitude of a ripper tool by utilizing a depthcontrol circuit to initiate a change in pitch when the ripper tool isdetected at a preselected depth and to utilize a pitch control circuitto terminate the change in pitch when the ripper tool is detected at apreselected pitch.

Still another object is to provide such a control device which includescomplementary circuitry to change the pitch to one setting when theripper tool is descending and to change the pitch to another settingwhen the ripper tool is ascending such that the ripper tool will be at asteeper inclination when it is above a preselected depth for mostefficient penetration and will be at a more shallow inclination below apreselected depth for most efficient ripping.

A further object is to provide a system for controlling the verticaldisplacement and angular displacement of a ripper tool by mounting theripper tool on an articulated tool mount and selectively moving themount with a depth positioning power means and a pitch positioningmeans. Power is alternately applied to the respective positioning meansin response to a control means. The control means includes an automaticcomponent which determines which positioning means is operational andalso includes a manual component which determines the direction of powerimpressed on the positioning means.

Other objects include providing an automatic control device whichincludes circuits to allow overriding manual operation and also includescircuits to indicate the relative depth of the ripper tool and in whichmode it is operating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side elevational view of a tractor mountedripper device utilizing the preferred embodiment of control andillustrating the ripper tool penetrating the ground at a steep angle.

FIG. 2 is a view similar to FIG. 2 illustrating the ripper tool changedto a more shallow angle at a preselected depth.

FIG. 3 is a diagrammatic view of the control device of the instantinvention illustrating the control panel and fluid power circuit.

FIGS. 4 and 4A show a schematic view of the electrical circuit of thecontrol device.

FIG. 5 is an elevational view similar to FIG. 1 and illustrating anotherembodiment utilizing a different ripper mounting structure.

FIG. 6 is a view of the device in FIG. 5 illustrating the change inangular attitude of the ripper tool at a selected depth.

FIG. 7 is a fragmentary sectional view of one of the sensing switchdevices employed with the control device of FIGS. 1 and 2.

FIG. 8 is a transverse sectional view taken substantially along theplane of line 8--8 of FIG. 7.

FIG. 9 is a fragmentary view of a rotary sensing switch device as usedwith the embodiment of FIGS. 5 and 6.

FIG. 10 is a view taken substantially along the plane of line 10--10 ofFIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIGS. 1 and 2 there is shown a tractor mounted ripper tool 12 havingan articulated tool mount 13 for attachment to the rear of tractor 14.Ripper tool 12 has an upstanding shank 16 terminating at its lower endin a forwardly extending portion on which replaceable ripper blade 17 isaffixed. Ripper blade 17 has a chisel shape that tapers toward theleading edge about a horizontal medial plane 18. The angular attitude orpitch of the blade is defined by this plane.

The upper end of shank 16 is connected to shank bracket 19 by pins 21.Shank bracket 19 has a forwardly extending yoke 23 pivotally carried ontool beam 24 so that the ripper may swivel about vertical pin 26 andtrack the course of the tractor. Tool beam 24 is an elongated horizontalmember extending transversely across the rear of the tractor and maysupport a plurality of ripper shanks thereon.

Articulated tool mount 13 is in the form of a four bar link mechanism 27combining a series of links to support the tool beam and associatedripper tools for angular and vertical movement relative to the tractor.While the links are in laterally spaced pairs across the rear of thetractor, only one set will be described. Upstanding link 31 is rigidlyattached to tool beam 24. Lower trailing link 32 is pivotally attachedto the lower end of upstanding link 31 by pin 33 and extends therefromto pivot pin 34 on the lower end of support bracket 36. Support bracket36 is vertically positioned and rigidly attached to the rear of tractor14. Upper link 37 is formed by cylinder 38 and piston rod 39. The innerend of cylinder 38 is pivotally attached to the top of support bracket36 by pin 41 while the outer end of piston rod 39 is carried by pivotpin 42 at the top of upstanding link 31. Applying fluid power to thealternate ends of the piston of cylinder 38 allows the geometry of thefour bar link mechanism to be changed as described hereinafter.

Depth positioning means 43 is operatively connected to tool mount 13 andis formed to raise and lower ripper tool 12. Depth positioning cylinder44 and piston rod 46 is situated between the laterally spaced pairs oflinks and extends from the top of rear support bracket 36 to lowertrailing link 32. The upper end of cylinder 44 is pivoted on pin 47 andthe distal end of piston rod is pivoted on link by pin 49. Fluid poweralternately applied to the operative ports at the ends of cylinder 44will alternately raise the tool mount to an elevated position adjacentrear support bracket 36 and lower the tool mount to a position overlyingthe surface of the ground where ripper tool 12 will penetrate theground, as shown in phantom line in FIG. 1.

Similarly, pitch positioning means 51 is formed by cylinder 38. Fluidpower alternately applied to the operative ports at the ends of cylinder38 will alternately swing link 31 about pin 33 and change the pitch ofripper tool 12 as shown in phantom line in FIG. 2.

As mentioned hereinbefore, it is desirable to have the pitch of theripper blade at a steep angle when penetrating the ground and then tochange the pitch angle to a more shallow attitude at a preselected depthfor the ripping operation. It is for this change that an automaticcontrol means is provided to selectively apply fluid power to cylinder44 and cylinder 38 in the proper sequence.

As shown in FIG. 3, a fluid circuit 52 is provided which is controlledby output line 45 of an electrical control circuit housed in console 50.Console 50 is housed in the cab of tractor 14 and presents on its faceplate, dials and visual display for preselecting settings and indicatingconditions under which the control is working.

Fluid circuit 52 includes pump 53 supplying hydraulic fluid underpressure to line 54 from reservoir 55. Pressure line 54 leads tomanually operated control valve 56 while drain line 57 leads from valve56 to reservoir 55. Control valve 56 is a four-way three position valvewhich can connect pressure and drain lines 54 and 57 to first and secondconduit lines 58 and 59 or to close the conduit lines and recycle fluidfrom pump 53 back to reservoir 55. Conduit lines 58 and 59 are connectedto diverter valve 61 and also have branch lines 62 and 63. Divertervalve 61 is well-known in the trade and diverts fluid from conduit lines58 and 59 to either lines 66 and 67 or lines 68 and 69. Lines 66 and 67lead respectively to the top and bottom operative ports of depthpositioning cylinder 44 while lines 68 and 69 lead respectively to thefront and rear operative ports of the pitch positioning cylinder 38.From the foregoing circuit it will be seen that by proper manipulationof manual control valve 56 and diverter valve 61 fluid power from pump53 may be applied to the depth positioning cylinder 44 to depress orelevate the ripper tool or to apply fluid to the pitch positioningcylinder 38 to flatten or steepen the pitch angle of the ripper blade.Also, it should be noted that manual control valve 58 selects thedirection of travel of the cylinder pistons by alternately connectingpressure and drain lines 54 and 57 to conduit lines 58 and 59, whilediverter valve 61 selects the cylinder to which conduit lines 58 and 59are connected and determines which cylinder is operational at any onetime.

Manual control valve 56 is shifted by hand stick 71 provided in the cabof the tractor 14. Diverter valve 61 is shifted by fluid pressure frombranch lines 62 and 63 and lines 72 and 73 as directed by electricallyoperated control valve 74. Control valve 74 is a solenoid actuatedfour-way two position valve having inlet pressure and exhaust lines 76and 77 connected to branch lines 62 and 63 in tandem through lines 78and 79 and lines 81 and 82. Lines 78 and 79 have check valves 83 whilelines 81 and 82 have check valves 84 positioned in the oppositedirection. Thus, line 76 will have pressure and line 77 will be atexhaust irrespective of the condition of conduit lines 58 and 59.

Electrically operated control valve 74 is shifted by solenoid 84 orreturn spring 86 in response to the presence or absence of an electricalsignal from output lead 45 of an electrical control means in console 50.The generation of this signal will be described in detail later, but inthe instant invention the signal is initiated when the ripper tool isdetected at some preselected depth and the signal is terminated when theripper tool is detected at some preselected pitch. Thus, as the operatordirects fluid power through manual valve 56 to conduit line 58 the fluidwill first be applied to depth positioning cylinder 44. When the rippertool is detected at some preselected depth, a control signal isinitiated and control valve 74 will change the position of divertervalve 61 to apply fluid to pitch positioning cylinder 38.

Thereafter, when the ripper tool is detected at some preselected pitch,the signal will be terminated and control valve 74 will repositiondiverter valve 61 to once again apply fluid power to depth positioningcylinder 44. This sequence will work in both the descending andascending modes of operation. It will be seen that the only action theoperator has to make is to direct fluid to either lower or raise theripper tool and that the pitch of the tool will automatically be changedat a preselected depth. Thus by preselecting on the console switches thedesired raised pitch and rip pitch settings and the depth at which thepitch change will occur, an automatic and reocurring sequence isperformed without the conscious effort of the operator.

Provision is also made in the console for selecting either automatic ormanual operation and for indicating whether the ripper blade is above,at, or below some preselected depth.

FIG. 4 is a schematic diagram of the preferred form of the electricalcontrol circuit used in the present invention for controlling andindicating the position of the ripper tool. Looking at the drawing a fewobservations may be made. Generally, a depth control circuit 92 having adepth sensor means 93 and a depth selector means 94 are in the upperright of the drawing. A pitch control circuit 96 having a pitch sensor97 and a pitch selector means 98 is in the upper left. A control circuit99 having control means 101 and the solenoid 84 of the electric controlvalve 74 is in the lower left. A depth indicator circuit 102 ispositioned in the lower right. Other controls and indicator lamps arealso included as will be noted.

Also, as general observation, the depth control circuit 92 and pitchcontrol circuit 96 are serially connected with control circuit 99 suchthat an output will be generated if they are both in a conducting state.Further, the depth control circuit 92 and pitch control circuit 96 eachhave parallel wired first and second component circuits which areconnected to first and second control circuits and provide differentcircuitry for changing the pitch depending upon whether the ripper toolis descending or ascending.

Specifically, electrical power is supplied to the electrical controlmeans 50 from the tractor electrical system by lines 103 and 104. Line103 leads to one side of the depth control circuit through depth sensormeans 93. Line 104 leads to one side of the pitch control circuitthrough line 105, auto-manual selector switch 107 and pitch sensor means97. Auto-manual selector switch 107 chooses the mode of operation whilelamp 108 indicates tha automatic mode is operational.

Depth sensor means 93 has a plurality of normally open switch contacts111, one side of each is connected in common with line 103. Switchcontacts 111 are arranged along a line and switch actuating mechanism112 is movable along the line to sequentially close individual switchcontacts in relation to the instantaneous depth position of the rippertool. The structure for accomplishing this will be discussedhereinafter, but for the schematic showing in FIG. 4, it can be regardedthat the switches are stationary and the switch actuator moves up anddown with the ripper tool mount.

Depth selector means 94 is a rotary selector switch 113 having a movableswitch arm 114 and a plurality of contacts 116 electrically connected bylines 117 to corresponding contacts 111 of depth sensor means 93. Aseries connection will be made between line 103 and switch arm 114 whenswitch actuating mechanism 112 closes the corresponding switch contact111 of sensor 93 to the contact 116 selected on depth selector 94. Asmentioned, two depth control circuits are provided. First and seconddepth selector switches 113 and 118 are wired in parallel with eachother to lines 117 but with the contacts of second depth selector switch118 connected to the next succeeding corresponding contact of the sensorcontacts 111. Since first and second selector switches 113 and 118 havetheir switch arms ganged together, this wiring method provides an outputthrough first selector switch 113 before second selector switch 118 whensensor switches 111 are closed in descending order and converselyprovides a prior output through second selector switch 118 when thesensor switches 111 are closed in ascending order. At this time, itshould be noted that the depth control circuit 92 initiates a change inpitch and that the pitch control circuit 96 terminates the change inpitch. The necessity of having two depth control circuits will be moreapparent when compared with the two component pitch control circuits 96and the two component control circuits 99.

Pitch control circuit 96 includes pitch sensor means 97 having aplurality of normally closed switch contacts 119 arranged along a lineand switch actuating mechanism 121 movable along the line tosequentially open individual switch contacts in relation to theinstantaneous pitch position of the ripper tool. Similar to depth sensor93, it may be regarded that the switches are stationary and the switchactuator 121 moves in and out depending on whether the tool is moving ina steeper or more shallow direction.

First and second pitch selector switches 122 and 123 are rotary switcheshaving movable switch arms 124 and 126 and a plurality of switchcontacts 127 and 128 electrically connected in parallel by lines 129 tocorresponding contacts 119 of the pitch sensor means 97.

First selector switch 122 selects the angle of the ripping pitch modeand second selector switch 123 selects the angle of the raised orpenetrating pitch mode. Interconnecting means 131 defines that theselected pitch on first selector switch 122 will not be steeper than theselected pitch on second selector switch 123. First selector switch arm124 supports bar 132 on pin 133. Second selector switch arm 126 has pin134 slidable in slot 136 of bar 132. Looking to the drawing, it will beseen that second arm 126 will never be any increments below first arm124 as determined by interconnecting means 131.

First pitch control circuit 96a will be conductive when thecorresponding switch contacts 119 of the pitch sensor 97 and first pitchselector switch 122 are both closed. Second pitch control circuit 96bwill be conductive when the corresponding contacts of pitch sensor 97and second pitch selector switch 123 are both closed.

First control circuit 99a includes first control means 101a. Secondcontrol circuit 99b includes second control means 101b. Each controlmeans is in the form of a relay having an actuating coil 137a and 137bconnected in series with their respective depth and pitch controlcircuits. Each relay further has contacts 108a and 108b for applyingcurrent to solenoid 84 of electrically controlled valve 74 in relationto the electrical states of their respective depth and pitch controlcircuits as impressed on coils 137a and 137b. This in turn positionsdiverter valve 61 such that if either pair of depth and pitch controlcircuits are electrically conductive the pitch positioning cylinder willbe operational and, if neither pair is conductive, the depth positioningcylinder is operational.

The electrical connection between the first control means 101a and thefirst depth control and first pitch control circuits includes line 141from depth selector switch 113 to one side of coil 137a through diode142. Line 143 leads from the other side of coil 137a to pitch selectorswitch 122 through a contact of relay 144 and sensor reset switch 145.

The electrical connection between the second control means 101b and thesecond depth control and second pitch control circuits includes line 146from depth selector switch 118 to one side of coil 137b through diode147. Line 148 leads from the other side of coil 137b to pitch selectorswitch 123 through another contact of relay 144 and sensor reset switch140.

Diodes 142 and 147 prevent transient signals from acting on relay coils137a and 137b. Relay 144 has actuating coil 151 responsive todifferential pressure switch 152. Differential pressure switch 152 issituated between conduits 58 and 59 in fluid circuit 52 to monitor thedifferential pressure in the lines. If manual valve 56 is moved toanother position, there will be a change in the pressure in conduitlines 58 and 59 and will result in the opening of differential pressureswitch 152 and the contacts of relay 144. This ensures that the pitchchange operation will be cancelled and diverter valve 61 repositioned tothe depth positioning mode if the operator moves manual valve 56 in theopposite direction during the pitch positioning mode.

Differential pressure switch 152 and is associated relay 144 providethat only one of the control circuits are operational at any one time.For instance, as shown, differential pressure switch 152 is closed toenergize relay 144 and complete the circuit through relay coil 137a.This will allow the first control circuit 99a to function depending onthe electrical states of the first depth control circuit 92a and firstpitch control circuit 96a. If the fluid flow is reversed by moving handstick 71, differential pressure switch will open and de-energize relay144 to complete the circuit through relay coil 137b. This will allowsecond control circuit 99b to function depending on the electricalstates of the second depth control circuit 92b and the second pitchcontrol circuit 96b.

Sensor reset switches 145 and 149 are situated at the extreme end ofpitch sensor means 97 and are tripped if switch actuator 121 overtravelsthe selected point of sensor contacts 119 and continues to the extremeupper end point. In such a position, the automatic mode may not be ableto be reestablished. In this eventuality, sensor reset switch 145 willopen preventing control means 99a from functioning. Sensor reset switch149 will also open isolating control means 99b and closing a circuit toreset lamp 153 through line 154 and sensor reset switch 156 on depthsensor means 93. If depth switch actuator 112 moves to its extreme endpoint of the depth sensor 93, switches 156 and 157 will be tripped.Switch 156 will by pass depth selector switch 118 and directly actuatecontrol circuit 99b through line 158. Switch 157 will close andsimilarly ensure that control circuit 99b is actuated irrespective ofthe condition of differential pressure switch relay 144 or reset switch149. This will cause the ripper tool to move to the raised pitchposition releasing the pitch positioning cylinder.

Control means 101 receives electrical current from line 103 through line61. Contacts 108a and 108b, when closed, apply this current through line162 to solenoid 84 as mentioned. Contacts 163a and 163b hold theirassociated relay coils 137a and 137b in an energized state through theclosed contacts of the pitch control circuit 96. This allows evenmomentary contact through the depth sensor means 93 to initiate a pitchchange cycle.

Manually operated switch 164 is situated on the top of stick 71 andprovides for energizing solenoid 84 through "auto-manual" selectorswitch 107 and line 166. "Pitch mode" indicating lamp 167 will belighted through line 168 when solenoid 84 is excited.

As an ancillary feature, a depth indicator 102 is included. The outputleads of depth sensor 93 are connected in parallel to three rotaryselector switches 169a, 169b and 169c. The switches are wired so thatswitch 169b has contacts 171b wired in common to corresponding contacts111 of the depth sensor 93 while switch contacts 171a are connected tothe next preceding sensor contacts 111 and switch contacts 171c areconnected to the next succeeding sensor contacts 111. Switch arms 172a,172b and 172c are ganged for coincident movement. Each arm iselectrically connected to an associated relay through lines 173a, and173b and 173c. Relays 174a, 174b and 174c have contacts 176 which whenclosed will light lamps 177a, 177b or 177c indicating that the rippertool is "above depth", "at depth" or "below depth". Furthermore, therelay contacts are wired and interconnected in a network such that oncea relay coil is energized, it will close contact 178 and remain in theenergized state until another relay is energized. For instance, if adepth sensor contact 111 corresponding to the contact on selector switch169b is closed, relay coil 179b becomes energized and closes itscontacts 176b and 178b. "At depth" lamp 177b is lighted through contact176b and relay coil 179b remains energized through contact 178b andthrough the contacts 176c and 176a of its neighboring relays. If depthsensor switch actuator 112 moves onto either the succeeding or precedingsensor contacts 111, one of the neighboring relays will be excited andcontact 176a or 176c will release the "at depth" relay 174b. The depthindicator circuit is actuated by switch 181 and is indicated inoperation on "depth indicator" lamp 182.

FIG. 4A illustrates a solenoid operated valve 183 which may be includedin the depth positioning section of fluid circuit 52 to always maintainthe tool above a specified depth. Lines A--A are connected to lines A--Ain the control circuit. If the tool is detected at the specified depth,solenoid operated two position two-way normally open valve 183 will beenergized and cut off the fluid flow to depth positioning cylinder 44through line 66. The tool may be raised upon flow reversal through theparallel check valve 185.

FIGS. 5 and 6 illustrate an alternate embodiment of tool mount 13A. Thefour bar link mechanism 27A is formed by solid links 184, 186, 187 and188 pivotally connected at their ends by pins 189, 191, 192 and 193.Depth positioning cylinder 194 is situated as in FIGS. 1 and 2 betweenpivot pins 196 and 197. Pitch positioning cylinder 198 is pivotallycarried on tool beam 199 by clevis 201 and extends diagonally upwardtherefrom. As fluid power is applied to the operative ports of cylinder198, piston rod 202 connected to pin 193 will swing tool beam 199 andassociated ripper tool 12A about pin 189 and change the pitch attitudeof the ripper tool.

FIGS. 7 and 8 illustrate the preferred form of sensor means as used onboth depth sensor 93 and pitch sensor 97 in the structure shown in FIGS.1 and 2. Sensor microswitches 203 are supported on longitudinal bars 204in cylindrical housing 206. Bars 204 are circumferentially spaced incylinder 206 and sensor switches 203 are equidistantly spaced along thebars 204. Actuating mechanism 207 is in tubular form supported for axialmovement in housing 206 on central support rod 208 through end cap 209.Support rod 208 is threadably connected to end plate 211 at the oppositeend of housing 206 from end cap 209. Inner end 210 of actuatingmechanism 207 has radially extending trip member 212 which sequentiallydepresses the switch arms of switches 203 as actuating mechanism 207 ismoved in housing 206. Electrical leads 213 from switches 203 areprotected in cable 214 between the sensors and console 50.

Looking to FIGS. 1 and 2, depth sensor 93 is connected to supportbracket 36 and lower link 32. As depth positioning cylinder 44 moveslower link 32, actuating mechanism 112 will move axially andsequentially actuate sensor switches 111 in relation to the depthposition of ripper tool 12 as shown in phantom line in FIG. 1. Pitchsensor 97 is supported on pitch positioning cylinder 38 while itsactuating mechanism 121 is operatively connected through clevis 216 oncylinder rod 39. As pitch positioning cylinder 38 moves link 31,actuating mechanism 121 will move axially and sequentially actuate thesensor switches 119 in relation to the pitch position of ripper tool 12as shown in phantom line in FIG. 2. In some instances it may bedesirable to elevate the depth sensor to a position above lower link 32such as to a position between upstanding link 36 and cylinder 38.

FIGS. 9 and 10 illustrate another form of sensor switch as used on thestructure of FIGS. 5 and 6. Actuating mechanism 217 is a series ofganged switch arms 218 carried on shaft 219. Shaft 219 is rotatablyjournaled in bracket 221 and is pinned to arm 222 at its outer end.Switch arms 218 have contact detents 223 at their outer ends whichoverride circumferentially spaced contacts 224 carried on discs 226.Discs 226 are supported on bracket 221 by spacer lugs 227. As shaft 219is rotated, switch arms 218 will sequentially contact individualcontacts 224 in relation to the angular position of arm 222.

Looking to FIGS. 5 and 6, depth sensor 93A is attached to the upper endof support bracket 187. Arm 222 pivotally carries one end of link 228while the lower end of link 228 is pivotally carried on arm 229. Arm 229is secured through pin 192 to move with link 188 of the four bar linkmechanism 27A. As depth positioning cylinder 194 moves tool mount 13A,arm 229 will move link 228 and arm 222 a proportional amount. Arm 222will rotate shaft 219 and attached switch arms 218 to sequentiallyoverride individual switch contacts 224 in relation to the depthposition of the ripper tool, as shown in phantom line in FIG. 5. Pitchsensor 97A is supported on line 184 and is coupled to the top of pitchpositioning cylinder 198 through arm 232, link 233 and arm 231. As pitchpositioning cylinder 198 moves tool beam 199, arm 232 will rotate shaft219 and attached switch arms to sequentially override individual switchcontacts in relation to the pitch position of the ripper tool, as shownin phantom line in FIG. 6.

In operation, determination is made as to the best penetrating andripping positions for the ripper tool. This information is programmedinto the automatic control means by selecting on the console switchesthe desired raised pitch and rip pitch and the depth at which the pitchchange will occur. A desirable working depth is also selected.

As an example, a desirable rip pitch of "2" is selected on first pitchselector switch 122, a raised pitch of "8" is selected on second pitchselector switch 123 and a pitch change depth of "5" is selected on depthselector means 94. A working depth of "11" is also selected on depthindicator switch 169. Auto-manual switch is put in the automaticposition and depth indicator switch 181 is put in the "on" position.

The operator manipulates stick 71 to set manual valve 56 to apply fluidunder pressure from pump 53 to conduit line 58 and through divertervalve 61 and line 66 to the top of depth positioning cylinder 44. Pistonrod 46 extends and acts through four bar link mechanism 27 to depressripper tool 12 into the ground. Depth sensor 93 monitors the position oftop mount 13. Actuating mechanism 112 sequentially closes depth sensorcontacts 111 in relation to the depth of ripper tool 12. When the depthsensor contact corresponding to "5" is closed, the depth control circuit92a is rendered conductive and current from line 103 is conducted alongline 117 to the selected contact 116 on selector switch 113 and throughswitch arm 114 and line 141 to one side of relay coil 137a. A conductivepath through pitch control circuit 96a to line 104 is provided on theother side of coil 137a through line 143, closed contacts of relay 144,closed switch 145, switch arm 124, line 129, closed pitch sensor contact119, and line 105a and closed switch contacts of 107.

Relay contacts 108a and 163a close in response to the excited state ofcoil 137a and conduct current from line 161 to keep the coil excited andalso through line 162 to solenoid 84 of electrically controlled valve74. Electrically controlled valve 74 shifts to apply fluid pressure fromline 76 to line 73. The fluid pressure shifts diverter valve 61 toconnect lines 58 and 59 with lines 69 and 68. Fluid power is nowdirected to pitch positioning cylinder 38 and extends piston rod 39 toact through tool mount 13 to change the pitch of ripper tool 12 to amore shallow angle. Pitch sensor 97 monitors the position of tool mount13. Actuating mechanism 121 sequentially opens pitch sensor contacts 119in relation to the pitch of ripper tool 12. When the pitch sensorcontact corresponding to "2" is opened, the pitch control circuit isrendered non-conductive and relay coil 137a is deenergized. Controlmeans contacts 108a and 163a open and remove electrical current fromline 161, solenoid 84 and coil 137a. Electrical control valve 74 shiftsunder pressure from spring 86 and directs fluid pressure through line 72to reposition diverter valve 61. Diverter valve once again connectsconduit lines 58 and 59 with lines 66 and 67 and makes depth positioningcylinder 44 operational.

The operator may continue to depress the ripper tool which is nowpositioned for a ripping mode of operation. Depth sensor means 93 willcontinue to monitor the depth of the ripper tool and will indicate tothe operator through depth indicator means 102 the relative depthposition of the ripper tool. The operator may raise and lower the rippertool as necessary for best ripping operation and the ripper tool willremain at the ripping pitch as long as the tool does not move above theselected pitch change depth.

After the ripping operation is completed, the operator elevates theripper tool by shifting manual control valve to connect pressure line 54with line 67 at the lower port of depth positioning cylinder 44. Thiselevates tool mount 13. Depth sensor 93 continues to monitor theposition of tool mount 13 by sequentially closing depth sensor contacts111. When the sensor contact, corresponding to the contact selected ondepth sensor switch 118, is reached, control means 101b is actuated.This in turn energizes solenoid 84 to shift control valve 74 andpositions diverter valve 61 in the pitch change mode. Pitch positioningcylinder 38 is supplied with fluid power and piston rod 39 moves toolmount 13 to put the ripper tool at a steeper angle. Pitch sensor 97monitors the position of tool mount 13 by sequentially opening pitchsensor contacts 119. When the sensor contact, corresponding to theselected contact of raised pitch selector switch 123, is opened, pitchcontrol circuit is rendered non-conductive and control means 101b isde-energized. This allows electrical control valve to be shifted byspring 86 and subsequently allows diverter valve to be repositioned inthe depth positioning mode.

Thus, if there is an electrical signal from either control means duringeither the descending or ascending modes, a pitch change will be made.If the operator should change the position of manual valve 56 duringthis pitch change, differential pressure switch 152 will open or closeand cancel the pitch change command by reverting to other mode.

From the foregoing, it will be seen that an automatic control device forripper tools is provided which will change the pitch of the ripper toolat a preselected depth and allows for positioning the tool for mostefficient operation.

I claim:
 1. A depth indicating means for indicating the relativevertical displacement of a tractor supported tool, said indicating meanshaving an above depth indicating circuit, an at depth indicating circuitand a below depth indicating circuit, each of said indicating circuitsrespectively including an above depth selector switch, an at depthselector switch, and a below depth selector switch each of which denotespresettable settings corresponding to depth settings of the tool, adepth sensor means responsive to the vertical displacement of the tool,said depth sensor being connected to all of said depth indicatingcircuits, said individual indicating circuits being activated inrelation to the detected position of the tool, each circuit furtherhaving visual indicating means for denoting which circuit is activated,further including an above depth activating relay coil, an at depthactivating relay coil and a below depth activating relay coil, andwherein each of said selector switches has a plurality of switchcontacts electrically connected to corresponding switch contacts of thesensor means, each selector switch further having a movable switch armserially connected with a corresponding one of said activating relaycoils, a pair of above depth relay contacts, a pair of at depth relaycontacts and a pair of below depth relay contacts each pair of saidrelay contacts being responsive to a corresponding one of said relaycoils and connected in an interconnected network with the relay coils ofthe other indicating circuits such that a coil activated by thecorresponding selector switch will remain energized until another relaycoil is energized through the sensor means and a selector switchassociated with said another coil, said visual indicating means furtherincluding an above depth visual indicating lamp, an at depth visualindicating lamp and a below depth visual indicating lamp, each pair ofsaid relay contacts connected to a corresponding one of said visualindicating lamps for indicating which circuit is energized.
 2. The depthindicating device as defined in claim 1, wherein said depth sensor meansincludes a switch contact activating means associated with the tool,said switch contact activating means being connected to said depthsensor means to sequentially operate said sensor means switch contactsin accordance with instantaneous depth of the tool.
 3. The depthindicating device as defined in claim 2, wherein said sensor meansswitch contacts are normally open switch contacts.
 4. The depthindicating device as defined in claim 2, wherein each of said depthindicating circuit selector switches are rotary selector switches. 5.The depth indicating device as defined in claim 4, wherein the movableswitch arms of the depth indicating circuits are ganged together.
 6. Thedepth indicating device as defined in claim 5, wherein each of theselector switch switch contacts of said above depth selector switch isconnected to a corresponding depth sensor selector switch switch contactwhich is immediately adjacent a depth sensor switch contact to which acorresponding switch contact of said at depth selector is connected.